This invention relates to an adjustable shock absorber, and more particularly, the invention relates to a shock absorber with a compression damping adjustment.
Shock absorbers are used in vehicles to dampen inputs from roadways. For some vehicle applications, such as snowmobiles, it may be highly desirable to provide the ability to easily adjust the damping characteristics of a shock absorber. For example, snowmobile ride characteristics may be affected due to the variation of weight from different and multiple passengers. The greater the vehicle""s and passenger""s static weight, the more the shock absorber will become compressed thereby lessening its damping capability. To this end, adjustable shock absorbers have been developed to permit the driver to adjust the damping characteristics of the shock absorber to accommodate varying weights and personal vehicle handling preferences.
Shock absorber damping may be changed by providing various valves and orifices through which fluid flows within the shock absorber. Inhibiting fluid flow will make the shock absorber stiffer, and increasing fluid flow will make the shock absorber softer. In the prior art, a driver could adjust the damping of the shock absorber by selecting from several distinct settings. A screw has been attached to a drum having orifice of different sizes arranged radially about the drum. As the screw was turned, a particular orifice was arranged in a fluid passageway to control the flow of fluid through the passageway. A detent mechanism was associated with the screw and drum such that the orifice was maintained in alignment with the passageway.
Alternatively, the stiffness of a spring biasing a blow-off valve has been varied to adjust shock absorber damping. A screw was used to load and unload the blow-off valve spring to control the flow of fluid through the valve. However, a single adjustment mechanism has not been provided to permit adjustment of both a blow-off valve and an orifice. Moreover, an adjustment member has not been provides that permits damping adjustment through an infinite number of positions. Therefore, what is needed is an adjustable shock absorber that provides a drive with increased adjustment of the flow through the shock absorber.
The present invention provides an adjustable shock absorber including a body having a fluid passageway with first and second passages in fluid communication with one another. A valve assembly is arranged between the passages and includes a plunger that is adjustable between a plurality of positions corresponding to a plurality of fluid flow positions. The valve assembly includes a metering valve having a orifice in a disc, and the plunger includes a needle with a portion disposed in said orifice to provide flow area. The flow area is changed when the plunger moves. The valve assembly also includes a blow-off valve in which the disc is biased to a closed position by a spring arranged between the plunger and the disc. Movement of the plunger changes the loading on the spring. An adjustment knob has a cammed surface that cooperates with the plunger so that as the adjustment knob is rotated the cammed surface moves the plunger. In this manner, the blow-off and metering valves may be adjusted simultaneously, or independently if the metering and blow-off valves are separated, to provide more desirable shock absorber adjustment. Moreover, adjustment of the shock absorber is not necessarily limited to a finite number of distinct positions.
Accordingly, the above invention provides an adjustable shock absorber that provides a drive with increased adjustment of the flow through the shock absorber.